What caused the "double Santa" issue when Hoody opened an Earthling present on level 4?

[Ryan fae Scotland]

Link to clip on Twitch: Surprise extra Santa - Twitch

Hoody is hammering through presents on level 4. He starts with 38 points, opens Rootbeer for 40 points (triggering a promo), then a Food, and then an Earthling. When the Earthling opens though, it spawns 2 Santas instead of 1, which then promptly fly off in slightly different directions.

What caused this duplication of the jolly fat man?

[Ryan fae Scotland]

I looked into this a little by tweaking the Earthling present to always give a Santa. Opening 2 of them causes a crash.